It's less work to put a proper boot on over a stretch boot given that it is possible to do without removing the outer CV from the hub upright.
I've not seen these open wrap around and seal boots that this thread is about though, it sounds like a total bodge waste of time though.
Search this forum for ideas, no larger more powerful engine will bolt in easily, all will require engine mount fabrication and bespoke drive-shafts, as an example look at this thread https://www.micra.org.uk/threads/my-k11-sr20de-t-thread.68840/
You may find this thread of interest, Pete also has 3 other build threads in a similar vein http://sxoc.com/vbb/showthread.php?580404-The-final-hurrah-%C2%96-S13-25K-miles-1-owner-from-new-full-refurb
Having seen tests done with Waxoyl I've gone right off it, Bilt Hamber stuff works much better. https://www.bilthamber.com/corrosion-protection-and-rust-treatments/
There comes time when age means the price starts to go up. Did a quote for my Dad who is older by more than 10 years and it was nearly 4 times your premium.